Weeds acquire genes from engineered crops

Way back in 2001, New Scientist reported that genetically modified (GM) oilseed rape, known as canola in North America, was being grown so widely in Canada that many plants had "escaped" from fields and become weeds. Most had been made resistant to broad-spectrum weedkillers such as Monsanto's glyphosate, but the analysis we reported showed that some had acquired additional resistance by cross-breeding with modified crops that were resistant to other herbicides.

Despite this, no panic buttons were pressed, and farmers learned to manage the problem by rotating crops. That means different herbicides are used on a single plot of land, which helps wipe out weed-resistant survivors.

Now, 10 years on, similar "stacked" hybrid canola weeds are being found in the US. Meredith Schafer of the University of Arkansas at Fayetteville reported at the annual meeting of the Ecological Society of America in Austin, Texas, this week, that she had found "escaped" canola plants in North Dakota that were resistant both to glyphosate, sold by Monsanto as Roundup, and to glufosinate, sold by Bayer Cropscience as LibertyLink.

As in Canada a decade ago, the discovery is a good demonstration that
genes do get about in the wild. Neither company would have engineered
resistance against a rival weedkiller into their own plants, so the only
explanation is that the extra gene was acquired "naturally".

Several scenarios could explain how this happened, says Schafer, who conducted the project with her superviser, Cynthia Sagers.
"It could have happened if one farmer planted glyphosate-resistant
canola, and his neighbour planted glufosinate-resistant canola, for
example." Canola plants escaped as weeds from one field could have been
fertilised by pollen from the other, leading to a doubly resistant weed.

Schafer made the discovery during a comprehensive survey of
North Dakota, a US hub of GM canola production, to find out how
widespread GM canola weeds had become. She found canola at 288 out of
631 sampling sites on roadsides throughout the state, and of this, 80
per cent was genetically engineered, with resistance to one or other of
the two weedkillers. She found two plants, just 0.7 per cent of the
total, with double resistance.

"This is not a huge problem yet," she told New Scientist.
"The sky is not falling in." But she says it is the first evidence of
GM canola outside the crop system in the US, a finding which deserves
further investigation and caution, both by GM companies and by farmers,
in order to avoid spawning too many weeds with resistance to multiple
weedkillers.

The
take-home message is that while GM crops have delivered benefits for
farmers and the environment, there is still need for caution to prevent
spread of resistance, both to "feral" crop escapees and to natural
weeds. After all, what better way for Monsanto and Bayer to destroy
their own markets than for all weeds to become immune to their own
weedkillers? Now that would be some own goal.

No offence to the writer, but what is NOT obvious about this. If you plant crops in a field some will escape, GM or not, and unless you cripple their reproductive process they will stand a chance of pollenating wild counterparts as most are insect pollenated. Every farmer knows this and surely every plant scientist knows this so where is the originality in this research.

Al
on August 9, 2011 2:23 PM

Some people who support GM argue that genetic alterations have been happening naturally for a very long time, and that farmers have been breeding and selecting varieties for thousands of years.

The genes of species change naturally, and over time nature tries out many different combinations, but for each species radical changes are unlikely, especially if they take a creature too far away from it's normal survival methods - it's ecological niche. Conventional breeding methods push species to extreme forms of variations that are already possible in nature, and they only use genes from the same or very similar species. Usually these extreme forms cannot survive in the wild. If they could they might well be living there already. But what we now call genetic modification is radically different. Scientists can take a gene from a starfish and put it into a strawberry, something that cannot happen in nature, or even in a conventional breeding program. It is even possible to invent completely new genes.

Think what happens when we introduce a new species from another continent. Silver carp, african bees or knotweed are introductions which have all proved disastrous. In some cases the organism itself is not much of a problem, to us but the impact it has on the balance of nature is devastating. When presented with a powerful new competitor, some native species can evolve with astonishing speed to adapt to the change in their ecological niche. They then put pressures on all the organisms that normally interact with them, which then affect the next species. Or species disappear, affecting the ecological balance, and the effect can be passed on through the network.
Another type of problem happens when the environment is altered by a new species. Recently earthworms have been introduced to North America. Their holes are changing the way that water flows through the soil, and air diffuses into the ground, and they are removing fallen leaf cover. That cover provides protection to native species which may not survive the introduction. If those species go extinct they will leave a hole in the ecology which will have further effects.

Proving that a particular modified gene is not going to do direct harm to the environment or the consumer is only the start of reassuring us. We should be asking them to prove that if these new genes get into a species which reproduces and spreads in the wild, and it begins to interact with existing wild creatures and the environment, then the changes in ecosystems will not be permanent and harmful. Particularly, when these evolutionary changes reflect back and forth through the ecosystem, will they knock out food crops, supercharge human diseases, or encourage pests? Will they increase floods, droughts, or atmospheric changes? Natural evolution occasionally comes up with a new species that causes ripples like this. But GM could cause many more, and more fundamental disruptions in much less time. Until we have a far better understanding of these very complex ecological systems we cannot begin to judge the safety of GM crops. But we can say that overall, the effects will contain some very nasty surprises.

Tony
on August 9, 2011 5:29 PM

The biggest problem is that Monsanto can grow a GM crop next door to a farmer who is growing a GM free crop and cross polinate that crop. Not only does the GM free farmer lose the value of his crop but he is also liable to Monsanto for the genes that they introduced to his crop. It sounds to me like money talks in the hallowed halls where laws are made if sort of travesty can occur.